THURSDAY, Oct. 24 (HealthDay News) -- Americans' levels of "good" cholesterol are improving, but total cholesterol levels haven't changed one way or the other in the past few years, U.S. health officials reported Thursday.

Meanwhile, the nation's screening rates for cholesterol have stalled, according to the new analysis from the U.S. Centers for Disease Control and Prevention.

Cholesterol levels include several components. With total cholesterol, low levels are healthier. In contrast, for high-density lipoprotein (HDL) -- the "good" cholesterol -- low levels are a risk factor for heart disease, while high levels are considered protective.

The CDC reported that compared to 2009-2010, fewer Americans aged 20 and older had low levels of good cholesterol in 2011-2012.

The percentage dropped by 20 percent -- to 17 percent of adults having low levels of good cholesterol.

According to lead report author Margaret Carroll, a CDC statistician, "the Healthy People 2020 goals for high total cholesterol of no more than 13.5 percent has been met for all groups except women."

But the goal of having at least 82.5 percent of Americans screened for cholesterol is lagging, she added.

The new analysis revealed that the rate of screening for cholesterol -- about 70 percent -- hasn't changed.

The lack of progress made in screening for total cholesterol "is of substantial concern," said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles.

"Earlier reports from the CDC have demonstrated declining trends in the percentage of U.S. adults with high total cholesterol in the past decade," noted Fonarow, who is also a spokesman for the American Heart Association (AHA).

However, "Cardiovascular disease remains the leading cause of death in men and women in the United States," he pointed out.

The new report found that proportions of adults with high total cholesterol and low good cholesterol varied by sex, race and ethnic group.

More women (about 14 percent) than men (11 percent) had high total cholesterol, and more women than men (72 percent versus 67 percent, respectively) had been screened for cholesterol, the researchers found.

But fewer women than men had low levels of good cholesterol (9 percent versus 26 percent, respectively), the study authors found.

In addition, the researchers found that fewer blacks had high total cholesterol than white men and women and Hispanic men. Total cholesterol was higher, however, among Hispanic women.

Moreover, blacks were less likely to have low levels of good cholesterol than whites, while Hispanics were the least likely to have low levels of good cholesterol. And Asians had lower levels of good cholesterol than Hispanics, according to the report.

Among Asian men and women the percentage with high total cholesterol wasn't significantly different from the other racial and ethnic groups, the researchers noted.

The investigators also found Hispanics were less likely to be screened for cholesterol than blacks, whites or Asians.

To gather these data, the CDC researchers used the U.S. National Health and Nutrition Examination Surveys from 2009-2010 and 2011-2012.

AHA's Fonarow noted that there are ways to improve cholesterol levels.

Many fatal and nonfatal heart attacks and strokes would be avoided with better detection of high cholesterol -- and lowering it by living a healthy lifestyle and, when needed, taking medications such as statins, he said.

"Efforts are urgently needed to improve cardiovascular health and reduce death and disability due to heart disease and stroke," Fonarow said.

People can also reduce these risks by being physically active, maintaining healthy blood pressure, achieving healthy body weight and not smoking, he added.